build: switch from SYSLINUX to GRUB2

The new grub install script must be called after the image is unmounted
and the old bootloaders script doesn't need to touch grub at all. For
now we will continue to use the existing syslinux configs but
interpreted by grub. Beyond the grub menu flashing by during boot
everything should still be functionally equivalent.

build_library/build_image_util.sh

@@ -204,6 +204,7 @@ finish_image() {
   local disk_layout="$2"
   local root_fs_dir="$3"
   local image_contents="$4"
+  local install_grub=0
 
   local disk_img="${BUILD_DIR}/${image_name}"
 
@@ -220,10 +221,10 @@ finish_image() {
 
   # Only configure bootloaders if there is a boot partition
   if mountpoint -q "${root_fs_dir}"/boot; then
+    install_grub=1
     ${BUILD_LIBRARY_DIR}/configure_bootloaders.sh \
       --arch=${ARCH} \
       --disk_layout="${disk_layout}" \
-      --disk_image="${disk_img}" \
       --boot_dir="${root_fs_dir}"/usr/boot \
       --esp_dir="${root_fs_dir}"/boot \
       --boot_args="${FLAGS_boot_args}"
@@ -249,4 +250,13 @@ finish_image() {
   rm -rf "${BUILD_DIR}"/configroot
   cleanup_mounts "${root_fs_dir}"
   trap - EXIT
+
+  # This script must mount the ESP partition differently, so run it after unmount
+  if [[ "${install_grub}" -eq 1 ]]; then
+    local target
+    for target in i386-pc x86_64-efi; do
+      ${BUILD_LIBRARY_DIR}/grub_install.sh \
+          --target="${target}" --disk_image="${disk_img}"
+    done
+  fi
 }

build_library/configure_bootloaders.sh

@@ -24,7 +24,6 @@ DEFINE_string boot_args "" \
   "Additional boot arguments to pass to the commandline (Default: '')"
 DEFINE_string disk_layout "base" \
   "The disk layout type to use for this image."
-DEFINE_string disk_image "" "The disk image."
 
 # Parse flags
 FLAGS "$@" || exit 1
@@ -52,6 +51,7 @@ SYSLINUX_DIR="${FLAGS_boot_dir}/syslinux"
 
 # Build configuration files for pygrub/pvgrub
 configure_pvgrub() {
+  info "Installing legacy PV-GRUB configuration"
   sudo mkdir -p "${GRUB_DIR}"
 
   # Add hvc0 for hypervisors
@@ -68,18 +68,21 @@ title           CoreOS B Root
 root            (hd0,0)
 kernel          /syslinux/vmlinuz.B ${grub_args} ${slot_b_args}
 EOF
-  info "Emitted ${GRUB_DIR}/menu.lst.A"
 
   sudo_clobber "${GRUB_DIR}/menu.lst.B" <<EOF
 default         1
+$(< "${GRUB_DIR}/menu.lst.A")
 EOF
-  sudo_append "${GRUB_DIR}/menu.lst.B" <"${GRUB_DIR}/menu.lst.A"
+  sudo cp "${GRUB_DIR}/menu.lst.A" "${GRUB_DIR}/menu.lst"
-  info "Emitted ${GRUB_DIR}/menu.lst.B"
+
-  sudo cp ${GRUB_DIR}/menu.lst.A ${GRUB_DIR}/menu.lst
+  # menu.lst needs to go under boot/grub so pvgrub can find it reliably
+  sudo mkdir -p "${FLAGS_esp_dir}/boot/grub"
+  sudo cp "${GRUB_DIR}/menu.lst" "${FLAGS_esp_dir}/boot/grub"
 }
 
 # Build configuration files for syslinux
 configure_syslinux() {
+  info "Installing legacy SYSLINUX configuration"
   sudo mkdir -p "${SYSLINUX_DIR}"
 
   # Add ttyS0 as a secondary console, useful for qemu -nographic
@@ -91,7 +94,6 @@ configure_syslinux() {
   fi
 
   sudo_clobber "${SYSLINUX_DIR}/syslinux.cfg" <<EOF
-SERIAL 0 115200
 PROMPT 1
 # display boot: prompt for a half second
 TIMEOUT 5
@@ -109,22 +111,10 @@ include /syslinux/root.A.cfg
 # coreos.B
 include /syslinux/root.B.cfg
 EOF
-  info "Emitted ${SYSLINUX_DIR}/syslinux.cfg"
 
-  sudo_clobber "${SYSLINUX_DIR}/default.cfg" <<EOF
+  sudo_clobber "${SYSLINUX_DIR}/default.cfg" <<<"DEFAULT boot_kernel"
-DEFAULT boot_kernel
+  sudo_clobber "${SYSLINUX_DIR}/default.cfg.A" <<<"DEFAULT coreos.A"
-EOF
+  sudo_clobber "${SYSLINUX_DIR}/default.cfg.B" <<<"DEFAULT coreos.B"
-  info "Emitted ${SYSLINUX_DIR}/default.cfg"
-
-  sudo_clobber "${SYSLINUX_DIR}/default.cfg.A" <<EOF
-DEFAULT coreos.A
-EOF
-  info "Emitted ${SYSLINUX_DIR}/default.cfg.A"
-
-  sudo_clobber "${SYSLINUX_DIR}/default.cfg.B" <<EOF
-DEFAULT coreos.B
-EOF
-  info "Emitted ${SYSLINUX_DIR}/default.cfg.B"
 
   # Different files are used so that the updater can only touch the file it
   # needs to for a given change.  This will minimize any potential accidental
@@ -135,7 +125,6 @@ label boot_kernel
   kernel vmlinuz-boot_kernel
   append ${syslinux_args} ${gptprio_args}
 EOF
-  info "Emitted ${SYSLINUX_DIR}/boot_kernel.cfg"
 
   sudo_clobber "${SYSLINUX_DIR}/root.A.cfg" <<EOF
 label coreos.A
@@ -143,7 +132,6 @@ label coreos.A
   kernel vmlinuz.A
   append ${syslinux_args} ${slot_a_args}
 EOF
-  info "Emitted ${SYSLINUX_DIR}/root.A.cfg"
 
   sudo_clobber "${SYSLINUX_DIR}/root.B.cfg" <<EOF
 label coreos.B
@@ -151,25 +139,9 @@ label coreos.B
   kernel vmlinuz.B
   append ${syslinux_args} ${slot_b_args}
 EOF
-  info "Emitted ${SYSLINUX_DIR}/root.B.cfg"
-}
 
-# Copy configurations to the ESP, this is what is actually used to boot
-copy_to_esp() {
-  if ! mountpoint -q "${FLAGS_esp_dir}"; then
-    die "${FLAGS_esp_dir} is not a mount point."
-  fi
-
-  sudo mkdir -p "${FLAGS_esp_dir}"/{syslinux,boot/grub,EFI/boot}
-  sudo cp -r "${GRUB_DIR}/." "${FLAGS_esp_dir}/boot/grub"
   sudo cp -r "${SYSLINUX_DIR}/." "${FLAGS_esp_dir}/syslinux"
 
-  # Install UEFI bootloader
-  sudo cp /usr/share/syslinux/efi64/ldlinux.e64 \
-    "${FLAGS_esp_dir}/EFI/boot/ldlinux.e64"
-  sudo cp /usr/share/syslinux/efi64/syslinux.efi \
-    "${FLAGS_esp_dir}/EFI/boot/bootx64.efi"
-
   # Stage all kernels with the only one we built.
   for kernel in syslinux/{vmlinuz-boot_kernel,vmlinuz.A,vmlinuz.B}
   do
@@ -177,28 +149,11 @@ copy_to_esp() {
   done
 }
 
-# Install GRUB2 to the disk image
-install_grub() {
-  # Install under boot/coreos/grub instead of boot/grub to prevent
-  # more recent versions of pygrub that attempt to read grub2 configs
-  # from finding it, pygrub and pvgrub must stick with using menu.lst
-  sudo mkdir -p "${FLAGS_esp_dir}/coreos/grub"
-  sudo grub-install \
-      --target=i386-pc \
-      --modules=part_gpt \
-      --boot-directory="${FLAGS_esp_dir}/coreos" \
-      "${FLAGS_disk_image}"
-  sudo cp "${BUILD_LIBRARY_DIR}/grub.cfg" \
-      "${FLAGS_esp_dir}/coreos/grub/grub.cfg"
-}
-
 [[ -d "${FLAGS_esp_dir}" ]] || die_notrace "--esp_dir is required"
-[[ -f "${FLAGS_disk_image}" ]] || die_notrace "--disk_image is required"
 
 if [[ "${FLAGS_arch}" = "x86" || "${FLAGS_arch}" = "amd64"  ]]; then
   configure_pvgrub
   configure_syslinux
-  copy_to_esp
 else
   error "No bootloader configuration for ${FLAGS_arch}"
 fi

build_library/disk_layout.json

@@ -13,7 +13,7 @@
         "blocks":"262144",
         "fs_type":"vfat",
         "mount":"/boot",
-        "features": ["syslinux"]
+        "features": ["hybrid"]
       },
       "2":{
         "label":"BIOS-BOOT",